Service transmission system related to relevant geographical zones and receiver designed to be used with said transmission system

ABSTRACT

The present invention relates to a transmission system for services which are linked to relevant geographic zones. Said system comprises at least one set of transmitters ( 1,2,3,4 ) transmitting said services to said zones ( 11,12,13,14 ) and a receiver ( 100 ) filled with a receiver sub-assembly ( 110 ) to receive said services, further with a locating unit ( 130 ) determining the said receiver&#39;s geographic zone and a switching unit ( 140 ) switching said receiver sub-assembly ( 110 ) to receive the service(s) linked to the relevant zones corresponding to the geographic position determined by said locating unit ( 130 ). In the invention, said transmission system or each transmitter will transmit simultaneously the services linked to the relevant zones under its coverage and the descriptions of the relevant zones ( 11, 12, 13, 14 ), also the addresses of said services as well as the descriptions of the relevant zones ( 11, 12, 13, 14 ) and the addresses of the zones neighboring the zones under coverage. The present invention also applies to a receiver used in conjunction with said transmission system.

The present invention relates to a transmission system for relevantgeographic zones and to a receiver being used together with saidtransmission system.

The technical field of the invention relates to transmitters that areset-up in predetermined zones and transmit information closely applyingto the geographically locations of said zones and of which theinterpretation also remains tied to the geographic location of thereceivers of such information. Illustratively such information mayrelate to road events such as a traffic jams and is significant onlywhen location specific and if the end user of said receiver is enabledto easily determine whether he/she is affected or not.

Broadcasting services providing information of road traffic already areavailable in Europe or are being standardized. As regards broadcastservices, they are based on an RDS/TMC standard.

Switching from a service assigned to a first zone to a service assignedto a second zone is implemented by switching the receiver from atransmitter of the first zone to a transmitter of a second zone, suchswitching being carried on the basis on one hand of location dataobtained from a locating system such as the global positioning systemGPS and on the other hand on data about the accurate geographic boundsof those services of which the broadcasts are likely to be received suchdata are permanently stored in the receiver.

Accordingly, while a receiver is set at transmitter broadcasting data toa first zone, when a vehicle passes from said first zone into a secondzone, the receiver shall know what services it has access to and thenwill seek the second zone data at the frequency of another transmitter.

Regardless of the geographic-content services, systems such as the oneknown as DAB (Digital Audio Broadcast) allow broadcasting dataspecifying the location of neighboring transmitters as well as theircoverage zone crudely represented by a mere rectangle, however omittingaccurate disclosure of contents of broadcast services.

The drawback of the known method of broadcasting information about suchrelevant zones is the present impossibility of transmitting informationrelating to an accurately defined relevant zone.

Either this zone transmission is restricted to crudely estimating therange of a transmitter (regardless of information content) to allowswitching between transmitters, or only the global range of the servicewill be indicated by one or more coarse regional parameters (“national”,“regional” . . . ).

Another drawback is that the relevant zones and hence the zones whereswitching will occur are stored in the receiver but cannot beautomatically radio-loaded in relation to receiver moves or to the dataincoming at this receiver. Therefore a new service requiring accurateswitching based on already extant services cannot be launched unless thereceivers be updated.

Accordingly it is the objective of the present invention to create aservices transmission system free of the above described drawbacks.

For that purpose a services transmission system of the inventionrelating to given geographic zones comprises at least one transmitter totransmit said services to said zones and one receiver fitted with areceiver sub-assembly accepting said service information, a locatingunit to determine the geographic position of said receiver and aswitching unit to switch said receiver sub-assembly to connect to theservice(s) linked to the relevant zone(s) corresponding to thegeographic position that was determined by said locating unit.

Said services transmission system is characterized in that eachtransmitter will simultaneously transmit the services linked to therelevant zones part of its coverage and the description of the relevantzones and the addresses of said services as well as the description ofthe relevant zones and the addresses of the services of the neighboringzones to those zones which partly overlap said portion of its coverage.

In another feature of the invention, at least one relevant geographiczone among said relevant zones is defined being overlapping at least oneneighboring relevant zone. Illustratively each relevant geographic zoneis defined by a set of geometric features, advantageously by a closedset of lines defining one or several polygons. Said at least one polygonmay be configured with at least one of its apices at given road markers.Some relevant zones also may be included rigorously in other relevantzones.

In another feature of the invention, and in addition to the descriptionof the relevant zones and the addresses of said services, eachtransmitter transmits optional information on data density and servicequality.

The present invention also relates to a receiver receiving serviceslinked to relevant geographic zones and transmitted by at least onetransmitter. This receiver is characterized in that it comprises alocating unit determining said receiver's geographic position, areceiver sub-assembly able to simultaneously receive the services linkedto the zones in which it is located together with the descriptions ofthe relevant zones and the addresses of said services plus thedescriptions of the relevant zones and the service addresses of thezones neighboring to its coverage, and a switching unit to receive saiddescriptions and to switch said receiver sub-assembly in order that itreceive the service(s) linked to the relevant zone(s) corresponding tothe geographic zone determined by said locating unit.

In another feature of the invention, said receiver also includes meansgiving the user the choice of driving the switching unit, in particularwhen the geographic position determined by said locating unitcorresponds to the boundaries of a relevant zone included in one or morerelevant zones.

In another feature of the invention, said receiver is designed toreceive—in addition to the description of the relevant zones and theaddresses of said services—also additional information of data densityand service quality. In this event said receiver includes means enablingthe user to drive the switching unit with regard to a selection of datadensity and/or service quality so that said switching unit be able toswitch said receiver sub-assembly to receive the service(s) linked tothe relevant zone(s) of which the data density and/or the servicequality shall correspond to said user's selection.

In another feature of the invention, the locating unit is fitted with anextrapolation function allowing knowing at any instant the vehicleposition based on the previously stored coordinates.

The above features of the invention as well as further ones areelucidated in the following description of an illustrative embodiment ofthe invention and in relation to the attached drawings.

FIG. 1 is a schematic of a services broadcasting system of the presentinvention, and

FIG. 2 is a summary schematic of a services broadcasting system receiverof the present invention.

The dotted lines in FIG. 1 represent the coverage zones 10, 20, 30 and40 of resp. transmitters 1 through 4.

Transmitter 1 transmits one or several services of which the relevantgeographic zone 11 is shown in FIG. 1. Be it borne in mind that severalservices may be transmitted to one relevant geographical zone.Transmitter 2 transmits services to its relevant zones 21, 22 and 23.Transmitter 3 transmits at least one service to a relevant zone 31.Transmitter 4 transmits services to relevant zones 41 and 42.

A relevant zone 32 is used for at least one service transmittedsimultaneously by the transmitters 1, 2, 3 and 4.

In the description herein, the term “transmission” is taken broadly andincludes broadcasting.

It is understood that, by being outside one of the given relevant zones,the services linked to said zone(s) are of no interest to the user.Illustratively this applies to road traffic services.

Be it noted that the relevant geographic zones of the servicestransmitted by a transmission system are not mandatorily within thecoverage of said transmitters. This is the case in FIG. 1 (for instancethe relevant geographic zone 31 is within the coverage 30 of thetransmitter 3) except for the relevant zone 32.

Each relevant geographic zone is determined by one or a set of featuresdefining a particular geometric shape. These may be features definingone or a set of circles, one or a set of ellipses, also a set ofcircles, lines, ellipses etc.

Advantageously at least one, or each relevant zone illustratively isdefined by a closed set of lines defining in this manner one or morepolygons.

In order to simplify defining the polygons by means of the coordinatesgenerally used in broadcasting road traffic services, a polygon whichdefines a relevant geographic zone will be situated by at least one ofits apices on road markers (mile signs, toll stations . . . ).

Also, to allow adequate service switching time, the zone topologies aresuch that two neighboring zones may overlap.

In the case of increasing-density services, the zones are defined sothat some of them, for instance zone 23 in FIG. 1, shall be situatedrigorously within other zones, in this case within zone 22.

In addition to transmitting services to the relevant zones it covers,each transmitter 1 through 4 transmits the descriptions of the relevantzones and of the addresses of said services and furthermore transmitsthe descriptions of the relevant zones and the service addresses ofthose zones which are neighboring to the coverage zones of theparticular transmitter.

Such descriptions may be complemented by optional information relatingto data density and service quality data.

FIG. 1 for instance transmitter 2 transmits the services for therelevant zones 21, 22 and 23 and 32, furthermore the definitions of saidservices, that is at least the description of said zones 21, 22 and 23and 32 and the addresses of the corresponding services. However it alsotransmits the descriptions of the relevant zones 11, 31, 41 and 42 andthe addresses of the corresponding services.

Illustratively a traffic information service relating to the Paris outersuburbs is available from a digital audio broadcast (DAB) system. Thisservice is defined by a relevance zone subtended by the inside of apolygonal line linking the toll stops of main highways leaving Paris andby a service address (frequency band and service number).

Another traffic information service is linked to the A6 highway betweenthe Fleury and Lyons tollbooths on a synchronous FM network. Thisservice will integrate a description of the relevant zone being within apolygonal line along the contours of A6 between the two preceding pointsand a service address (for instance the FM and a service number).

Illustratively zone 32 is one of synchronized broadcasting, that isbeing of the same frequency along the itinerary, when changingtransmitters but without switching the receiver.

Advantageously the neighboring relevant zones do overlap. For instancezone 22 overlaps zones 11 and 31 in FIG. 1.

FIG. 2 shows a receiver 100 to implement the method of the invention.Said receiver comprises a receiver sub-assembly 110 to receive thetransmissions from the services transmitters and to reproduce them by areproducing device 120, a locating unit 130 to feed the vehiclecoordinates C to a switching unit 140. The receiver sub-assembly 110also feeds the description D of the relevant zones to the switching unit140. If the coordinates C from the locating unit 130 correspond to theboundaries of a given relevant zone defined in the signal D, saidswitching unit will switch the receiver sub-assembly 110 to receive theservice linked to that relevant zone.

When the coordinates fed from the locating unit 130 correspond to theboundaries of a relevant zone which is within one or more other relevantzones, the user may drive the switching unit (signal U) to select eitherof said services.

In one embodiment variation and when the receiver sub-assembly 110 isdesigned to receive—in addition to the description of the relevant zonesand the addresses of said services—optional information about datadensity and service quality, the user also may drive the switching unitto select the data density and/or the service quality in such a way thatsaid switching unit be able to switch said receiver sub-assembly for thepurpose of receiving the service(s) linked to the relevant zone(s) ofwhich the data density and/or the service quality correspond to theselection of said user. It will be borne in mind that to the extentthere is overlap of the present relevant zone and the new one, the timeof switching may be delayed so as to be a less abrupt transition for theuser.

Moreover, if the locating unit 130 provides the vehicle coordinates atsubstantially long time intervals, said unit may be fitted with anextrapolating function allowing ascertaining at any time the vehicleposition based on the previously stored coordinates.

As regards FIG. 1, a user moving along the line xx′ receives theinformation from the transmitter 1 and consequently will receive theservice(s) of which zone 11 is the relevant zone. The receiver unit 110receives not only the description of the zone 11 and of thecorresponding service(s), but also the description of the zones 21, 22,23 and 32 and of the corresponding services.

When entering the relevant zone 32, the receiver sub-assembly 110 mayreceive either the services linked to the zone 11 or those linked to thezone 32. The selection shall be made by the user, either directly or byspecifying user-selected criteria in the manner described above.

Upon entry into the relevant zone 22, the switching unit 140 switchesthe receiver subs-assembly 110 on one hand toward the transmitter 2 andon the other hand toward the service(s) linked to the zone 22 or thezone 32. Delay in switching may take place.

Once within the coverage of zone 22 or zone 32, the receiversub-assembly 110 receives the service corresponding to that zone,further the description of this relevant zone 22, also that of the zones21 and 23, as a result of which, at entry into the zone 23, theswitching unit 140 is able to switch the receiver sub-assembly towardthe zone 23. However, said zone 23 being within the zone 22, the usermay intervene to dictate his choice.

Illustratively the zone 22 may define “Brittany” whereas the zone 23included in zone 22 will define a more specific, versatile and targetedservice, namely (city of) “Rennes”, (therein), such as travel time,parking lots etc.

Be it further borne in mind that when the zones 22 and 23 are covered,the receiver sub-assembly 110 also receives the definition of the zones11, 21, 31 and 41 (and possibly zone 42).

1. A transmission system for services linked to relevant geographiczones, said system comprising: at least one transmitter for transmittingsaid services into said relevant zones; a receiver comprising a receiversub-assembly for receiving said services, a locating unit fordetermining the geographic position of said receiver; and a switchingunit for switching said receiver sub-assembly for enabling said receiversub-assembly to receive at least one service linked to at least onerelevant zone corresponding to the geographic position ascertained bysaid locating unit wherein: while transmitting the services linked tooverlapping relevant zones, said transmitter is arranged to transmitdescriptions of the relevant zones, addresses of the services linked tothe relevant zones, and descriptions and addresses of services ofneighboring relevant zones.
 2. Services transmission system as claimedin claim 1, wherein at least one relevant geographic zone among saidzones overlaps at least one neighboring relevant zone.
 3. Servicestransmission system as claimed in claim 1, wherein each relevantgeographic zone is defined by a set of geometric features.
 4. Servicestransmission system as claimed in claim 3, wherein at least one relevantgeographic zone is determined by a closed set of geometric featuresdefining one or more polygons defining at least one polygon.
 5. Servicestransmission system as claimed in claim 4, wherein at least one apex ofat least one of said one or more polygons is coincident with roadmarkers.
 6. Services transmission system as claimed in claim 1, whereinsome of said relevant zones are included rigorously within others ofsaid relevant zones.
 7. Services transmission system as claimed in claim1, wherein each transmitter is also arranged to transmit optionalinformation about data density and service quality.
 8. A receiver forreceiving services linked to relevant geographic zones and transmittedby at least one transmitter, said receiver comprising: a locating unitfor determining a geographic position of said receiver; a receiversub-assembly which, simultaneously with said receiver, is arranged forreceiving: (a) the services linked to the zones wherein said receiver islocated, (b) descriptions of the relevant zones, addresses of theservices linked to the relevant zones, and (c) descriptions andaddresses of services of neighboring relevant zones; and a switchingunit for receiving said descriptions and switching said receiversub-assembly so that said receiver sub-assembly can receive at least oneof the services linked to at least one of the relevant zonescorresponding to the geographic position ascertained by said locatingunit.
 9. Receiver as claimed in claim 8, further including an actuatorfor enabling a user to activate the switching unit according to when thegeographic position determined by said locating unit corresponds toboundaries of a relevant zone situated within one or more other relevantzones.
 10. Receiver as claimed in claim 8, wherein said receiversub-assembly is arranged for receiving information on density data andservice quality, said receiver sub-assembly further including a userselector for enabling a user to select at least one of data density andservice quality applied to the switching unit such that said switchingunit is able to switch said receiver sub-assembly to receive theservice(s) linked to the relevant zone(s) of which at least one of thedata density and the service quality correspond to said user'sselection.
 11. Receiver as claimed in claim 8, wherein the locating unitis fitted with an extrapolation function for instantaneously determiningvehicle position based on previously sorted coordinates.
 12. A method oftransmitting services linked to relevant geographic zones, said methodcomprising: transmitting said services into said relevant zones;receiving said services at a receiver in one of said zones; determiningthe geographic position of said receiver; receiving at the receiver siteat least one service linked to at least one relevant zone correspondingto the determined geographic position; transmitting descriptions of therelevant zones, addresses of the services linked to the relevant zones,and descriptions and addresses of services of neighboring relevant zoneswhile transmitting the services linked to a plurality of the relevantzones that overlap.